const fs = require('fs');

const rs = fs.createReadStream('./a.txt',{highWaterMark:4});
const wx = fs.createWriteStream('./b.txt',{ highWaterMark: 1});
//对 on('data') write() end() close的封装
rs.pipe(ws);//这个方法是同步还是异步？异步，缺陷无法看到具体的过程

//pipe的目的是可以 读取一点写一点 监听可读取


